Rock drill



0a. 13, 1942. J. R. HICKS 2,298,792

v I ROCK DRILL I Filed June 27, 1941 v INVENTOR. /0/// Ro /1L fi/c/rs;

A T TOR/VI Y.

Patented Oct. 13, 1942 UNITED STATES PATENT 'QFFICE ROCK mum. John Royal Hicks, Sam-gents, 0010.

Application June 27, 1941, Serial No. 399,977 6 claims. ((1255943) This invention relates to an electric rock drill and has for its principal object the provision of a simple and highly efficient mechanism for driving rock drills which can be operated directly from a standard electric motor mounted directly upon the drill, thus, eliminating all air hoses, compressors, piping, etc.

Other objects of the invention are to provide a construction in which the blow delivered to the drill will be entirely independent of the speed or power of the motor; in which means will be provided for assisting the motor in returning the-hammer after the blow has been struck; to provide an efiicient construction by means of which the hammer portion of the drill can be quickly and easily removed and replaced when necessary.

Other objects and advantages reside in the detail construction of the invention, which is designed for simplicity, economy, and efficiency. These will become more apparent from the following description.

In the following detailed description of the in- I drawing and throughout the description.

In the drawing:

Fig. 1 is a plan View of one form of the improved rock drill;

Fig. 2 is a side view thereof;

Fig. 3 is an enlarged longitudinal section through the drill, taken on the line 33, Fig. 1;

Fig. 4 is a cross section, taken on the line 4-4, Fig. 3; I

Fig. 5 is a similar cross section, taken on the line 5-5, Fig. 3; and r Fig. 6 is a fragmentary side View of the barrel of the drill illustrating the elongated slots formed therein.

The improved drill may be supported on any kind of bed or bracket suitable for the particular job upon which it is to be used. It is provided with a dove-tailed base portion 10 by means of which it may be securely clamped to its support. The dove-tailed base is formed on a gear box II which is closed by means of a suitable cover plate 12. A tubular barrel I5 is formed on and projects forwardly from the gear box II. The forward extremity ofthe barrel I5 is internally threaded to receive a chuck sleeve 11 in which a drill chuck member 18 is slidably mounted to receive the head of a drill steel 19.

Like numerals refer to like 'parts in all views of the A cylindrical piston 29 is slidably mountedwithin the barrel l5. The piston is formed at its rear extremity with a recess 2| for receiving the head of a connecting rod 22. The connecting rod is mounted on a wrist pin 23 which extends entirely through the piston 29 and through the opposite sides of the barrel 15, through elongated slots 13 therein.

The extremities of the wrist pin 23 project oppositely outward from the barrel l5 through a sliding sleeve 25 on the exterior of the barrel [5. The other extremity of the connecting rod 22 terminates in a crank pin 26 which rides in an elongated circumferential slot 21 formed in a crank disc 28.

The crank disc is fixedly mounted on a crank shaft 29 extending outwardly through a bearing sleeve 30 in one side of the gear box II. The sleeve 39 extends inwardly to the crank disc 28 to prevent outward movement of the shaft.

Worm gear teeth I4 are formed in the periphcry of the crank disc 28. These teeth are in mesh with a toothed worm l6 secured on a worm shaft 24. The worm shaft is carried in pedestal bearings 31 "extending from the cover plate I2 so that the worm shaft may be removed by removal of the cover plate. The worm shaft carries a driven gear 32 which meshes with a drive gear 33 of an electric motor 34. The motor is provided with a mounting flange 35 which is secured to the rear wall of the gear box by means of suitable attachment screws 36.

A chuck collar 31 is secured on the forward extremity of the chuck sleeve [1 by means of a set screw 38. Hinge pins 39 project oppositely outward from the chuck collar to support a typical drill retaining yoke 49. A pair of hammer springs 4| extend between the extremities of the hinge pins 39 and the extremities of the wrist pin 23 at each side of the barrel [5.

It can be readily seen that as the motor operates, it will rotate the crank disc 28 in a counterclockwise direction, in Fig. 3. This causes the trailing extremity of the arcuate slot 21 to engage the crank pin 26, as shown in Fig. 3, so as to draw the piston 29 rearwardly. When the crank pin 26 passes the axial or dead center position of the disc 28, the springs 41 will operate to snap the piston forwardly, the crank pin traveling forwardly in the arcuate slot 21 without effecting the rotation to the crank disc 28.

It will be noted that the power of the motor is only utilized in stretching the springs 4| and that ordinarily during theremainder of the rotation of. the crank shaft no power would be required. The irregular absorption of power is counter-balanced by means of a counter-balance spring 42 which extends between a fixed spring pin 43 on the base I and a rotating spring pin 44 which is eccentrically carried on a spring disc 45 secured on the outer extremity of the crank shaft 29. Thus, while the motor is withdrawing the piston against the action of the springs 4|, the counter-balance spring is assisting the rotation of the crank shaft 29, as shown in Fig. 3. As soon as the motor is released from the reaction of the springs 4| the spring pin 44 will have reached a position where it will begin to stretch the counter-balance spring 42 during the idle cycle of operation. Thus, when not operating the piston 20, the motor is storingenergy by stretching the spring 42.

A hammer 46 is rotatably secured on the head' of the piston 20 by means of an axiallypositioned attachment screw 41. The screw 41 is locked, in place by means of a suitable cotter key 49. This hammer has a fluted head 48 extending into the drill chuck member l8 to a point where it may strike the head of the drill steel I!) therein at each forward stroke of the piston 20.

The yoke 40 prevents the drill from falling from the chuck member. The drill is rotated while drilling by means of a handle 58 projecting outwardly from a handle ring 5|: which is rotatably held on the chuck member I8 by means of a retaining collar 52 which is secured on the forward'extremity of the-chuck member by means of suitable set screws 53. The handle ring 5| rotates alongside a ratchet gear 54 which is secured on the chuck member l8 so asto'rotate therewith. A ratchet pawl 55, mounted on apawl pin 56 in the handle 59, engages the teeth of the ratchet gear at each reciprocation of the handle 50 to partially rotatethe chuck member I8- and through it the drill steel [9;

While a specific form of the improvement has been described and illustrated herein, it is desired to be understood that the same maybe varied, within the scope of the appended; claims, without departing from the spirit of the invention.

Having thus described the invention, what is claimed and desired secured by LettersPatent is:

1. An electrically driven rock drill comprising: a barrel; a piston slidably mounted in said-barrel; a chuck for receiving the rear extremity of a drill steel positioned at the forward extremity of said barrel; a hammer head on said piston to contact said steel; a crank disc positioned on a transverse axis at the rear ofsaid barrel, said disc-having a concentric circumferential slot extending substantially 180 about its axis; a connecting rod extending from said piston'to a position adjacent said disc; a pin in the extremity of said connecting rod entering said slot so that as said disc is rotated one extremity of said: slot will engage said pin to draw said piston awayfrom said steel; and spring means for drawing said piston toward said steel when said pin'passes the dead center position on said disc.

2. An electrically driven rock drill comprising: a barrel; a piston slidably mounted in said barrel; a chuck for receiving the: rear extremity of a drill steel positioned at the forward extremity of said barrel; a hammer head on said piston to contact said steel; a crank disc positionedona transverse axis at the rear of said barrel, said disc having a concentric circumferential slot extending substantially 180 about its axis; a connecting rod extending from said piston to a position adjacent said disc; a crank pin in the extremity of said connecting rod entering said slot so that as said disc is rotated one extremity of said slot will engage said pin to draw said piston away from said steel; a wrist pin securing said connecting rod to said piston, said connecting rod extending oppositely outward through longitudinally elongated slots in said barrel; and springs connected to the outwardly extending extremities of said wrist pin for drawing said piston forwardly when said arcuate slot releases the crank pin.

3. An electrically driven rock drill comprising: a barrel; a piston slidably mounted in said barrel; a chuck for receiving the rear extremity of a drill steel positioned at the forward extremity of said barrel; a hammer head on said piston to contact said steel; a crank disc positioned on a transverse axis at the rear of said barrel, said disc having a concentric circumferential slot extending substantially about its axis; a connecting rod extending from said piston to a position adjacent said disc; a crank pin in the extremity of said connecting rod entering said slot so that as said disc is rotated one extremity of said slot will engage said pin to draw said pistonaway from said steel; a wrist pin securing said connecting rod to said piston, said connecting rod extending oppositely outward through longitudinally elongated slots in said barrel; springs connected to the outwardly extending extremities of said wrist pin for drawing said piston forwardly when said arcuate slot releases the crank pin; and a sliding sleeve surrounding said barrel and moving with said wrist pin to conceal the elongated slots.

4. An electrically driven rock drill comprising: a barrel; a piston slidably mounted in sa d barrel; a chuck for receiving the rear extremity of a drill steel positioned at the forward extremity of said barrel; a hammer head on said piston to contact said steel; a crank disc positioned on a transverse axis at the rear of said barrel, said disc having a concentric circumferential slot extending substantially 180 about its axis; a connecting'rod extending from said piston to a position adjacent said disc; a pin in the extremity of said connecting rod entering said slot so that as said disc is rotated one extremity of said slot will engage said pin to draw said piston away from said steel; spring means for drawing said piston toward said steel when said pin passes the dead center position of said disc; and a second oppositely acting spring means acting on said disc to assist in rotating the latter against the resistance of the first spring means.

5. An electrically driven rock drill comprising: a barrel; a piston slidably mounted in saidbarrel; a chuck for receiving the rear extremity of a drill steel positioned at the forward extremity of said barrel; a hammer head on said piston to contact said steel; a crank disc positioned on a transverse axis at the rear of said barrel, said disc having a concentric circumferential slot extending substantiall 180 about its axis; a connecting rod extending from said piston to a position adjacent said disc; a pin in the extremity of said connecting rod entering said slot so that as said disc is rotated one extremity of said slot will engage said pin to draw said piston away from said steel; spring means for drawing said piston toward said steel when said pin passes the dead center position on said disc; gear teeth surrounding' the periphery of said disc; and a motor driven power transmission device engaging said teeth to' rotate said disc.

6. An electrically driven rock drill comprising: a barrel; a piston slidably mounted in said barrel; a chuck for receiving the rear extremity of a drill steel positioned at the forward extremity of said barrel; a hammer head on said piston to contact said steel; a crank disc positioned on a transverse axis at the rear of said barrel, said disc having a concentric circumferential slot xtending substantially 180 about its axis, a. connecting rod extending from said piston to a position adjacent said disc; a pin in the extremity of said connecting rod entering said slot so that as said disc is rotated one extremity of said slot will engage said pin to draw said piston away from said steel; spring means for drawing said piston toward said steel when said pin passes the dead center position on said disc; gear teeth surrounding the periphery of said disc; a worm in mesh with said teeth; an electric motor; and

transmission gears between said motor and said worm for transmitting the power thereto at re- 10 duced speed.

JOHN ROYAL HICKS. 

